Abstract:

Lower temperature stress is an ordinary natural occurrence during flue-cured tobacco seedling breeding. There is different resistance to lower temperature stress for different tobacco cultivars, but less tested evidence was available now. Five main cultivated flue-cured tobacco species ‘Yunyan 85’, ‘Yunyan 87’, ‘K326’, ‘Hongda’ and ‘Yunyan 97’ were selected as experimental material to compare the resistance in seed germination to lower temperature between flue-cured tobacco cultivars and to supply reference to selection and distribution of flue-cured tobacco species. Results showed that seeds of five cultivars could germinate in 5 days under normal temperature (25℃), but there were 1-2 days difference in time reaching maximum germination rate and ‘Yunyan 97’ was the last one. The germination potential, standard germination rate and germination index of five tobacco cultivars declined with environmental temperature decreasing. According to comprehensive comparison in germinating parameters of five cultivars, resistance to lower temperature of ‘Yunyan 97’ was weakest, and there was no obvious difference in resistance to lower temperature between other four cultivars. Lower temperature would constrain the germination rate and prolong seedling breeding, however under 10℃-25℃ environmental temperature, 95% final germination rate could be reached in 30 days.